Is the crown really that important?

[ZeSpectre]

I have long believed that the crown is vital to accuracy. But recently I noticed that my SKS has a small (thumbnail thickness) chunk missing from the edge of one of the lands of the rifling right at the crown inside the barrel. (I just can't figure out how it happened though, that's a little frustrating).

Now of course the SKS isn't renown for it's accuracy in the first place but mine is well into the "decent" category and the last shooting trip I took with it was no exception even given that missing chunk from the crown.

Does the SKS just have that much "play" where the crown really doesn't matter that much?

Does the crown really not matter as much as I've been led to believe?

Ze

 

[Dr. Dickie]

Don't know for sure. Don't have any facts to back up my wild belief. Only thing I do know is, it is the last thing the bullet touches on your gun.

 

[Medusa]

yes it is important, especially if the rifle is sub-moa, and even more when it's 1/2 moa or less. The SKS is not that accurate that you would start to notice the decrease in accuracy because of the crown alone. It really doesn't matter whether it's 2.5 or 3 moa.

 

[RubenZ]

Here is a thread that is also related to SKS.

http://thehighroad.org/showthread.php?t=66082&highlight=Crown+SKS

 

[ZeSpectre]

Thanks RubenZ, Did a quick search but missed that one.

 

[DogBonz]

Race Cars

How do race cars relate to guns? Well, like anything, the higher the level of performance, the more and more that the little things matter. Say your rifle shoots 1.5 – 2moa, then a nick in the crown may not matter much. If you have a bench rest rife, and you shoot .5moa all day long and .25 on Sunday, well then a scratch the size of the hair on a gnat’s derriere might ruin your day, and throw your groups to .75moa.

Also, and don’t quote me on this one, but I think that pressure plays a role in how important a crown is. I think that I remember reading that the higher the pressure, the faster the gasses exit the muzzle, and any inconsistencies or damage to the crown will exaggerate the turbulent nature of the rushing gas behind the bullet, thus throwing off accuracy. So the higher the pressure, the greater the importance of a smooth, concentric barrel crown.

 

[tegemu]

On any gun, damage to the crown will permit the escape of a small portion of the propellant gas at the point of damage, resulting in an uneven push to the bullet just as it departs the barrel. I don't see any way that crown damage can not adversly effect the flight of the bullet.

 

[Gewehr98]

The crown is the last point of contact for the bullet.

If it isn't "true", the bullet has every opportunity to tip or yaw as it departs.

I consider the condition of the muzzle crown to be even more important than the rifling, myself.

I have a 1917 Amberg 98 Mauser sporter in 8mm with a pitted bore and rounded rifling. To be honest, the rifling was consistent up to the muzzle, but the barrel had been bobbed by the previous owner, and it was a hack-job, not even close to being square or uniform.

I used a Brownell's 11-degree muzzle crown reamer and pilot to put a proper crown on the barrel. It was an effort to regain some accuracy before I replaced the rifle's barrel.

It shot so well, even with the dark bore, that I've yet to replace the barrel. I don't consider it "broken" any longer, so why fix it?



I've done the same for a friend's US M1917 Enfield sporter, again with a non-pristine bore and botched barrel hacksaw job, and it was well worth the effort to clean up the crown.

 

[Smokey Joe]

What means "decent"???

ZeSpectre--

the SKS isn't renown for it's accuracy in the first place but mine is well into the "decent" category and the last shooting trip I took with it was no exception even given that missing chunk from the crown.

So, what size groups are you getting with your badly crowned SKS, given ammo that it likes and whatever other good conditions you can arrange? For example, if you're already shooting 2" groups @ 100 yds, that is truly exceptional for a stock SKS, IMX, and were it mine, I'd be tempted in that case to leave well enough alone. However, if you call 6" groups "decent," it would probably be well worth your while to get the crown repaired--or DIY--and see what she's really capable of shooting.

I'm very much with Gewehr on this one.

 

[ZeSpectre]

I've only been able to take the SKS to a 100 yard range once so far. Benched I was getting (if I remember correctly) roughly 3.5" groups (maybe closer to 4") with Wolf military classic of all things.

 

[RNB65]

Wolf ammo is very inaccurate. I had my CZ Carbine (7.62x39) at the range yesterday shooting Wolf poly-coated ammo. Using a Nikon Monarch scope and with the rifle firmly bedded on front and rear rests, I was only able to get 3-4" groups at 100 yards. Sometimes I'd aim 2 consecutive shots at the exact same spot and they'd hit 3" apart.

 

[rangerruck]

If you like hitting what you are aiming at, then yes. You simply cannot have , right at the end of the bbl, a sudden drop, in lands, grooves gripping, pressure loss, and gas escaping, all the time, on one side of the bbl, if you want any accuracy.